Wind turbines are increasingly gaining importance as renewable sources of energy generation. In recent times, wind turbine technology has increasingly been applied to large-scale power generation applications. Maximizing energy output while minimizing loads of the wind turbines in varied wind conditions is a challenge that exists in harnessing wind energy.
A wind turbine typically includes a tower and a rotor rotatably coupled to two or more blades. The blades are acted upon by a wind flow to rotate the rotor. The speed of the wind turbine is dependent upon multiple factors including angle of attack, speed of wind, and pitch angle of a blade, for example. The angle of attack is an angle between a reference line of an airfoil of the blade and a direction of the wind flow acting upon the blade. The pitch angle of a blade of a wind turbine refers to a position of the blade with respect to the direction of the wind through which the blade rotates. The pitch angle of the blade may be changed to increase or decrease the speed of the wind turbine, and/or slowdown the wind turbine. Changing a pitch angle of a blade changes the angle of attack of the blade.
Typically, when a wind turbine is shut down, a pitch controller of the wind turbine changes the pitch angles of the blades of the wind turbine towards feather. However, changing the pitch angles of the blades towards feather when a rotor of the wind turbine is rotating at a high speed may induce high loads on the wind turbine. The loads, for example, may include tower top/hub loads and rotor imbalance loads and may lead to wear and tear of the wind turbine.
Therefore, it would be advantageous to provide improved systems and methods to shut down or slow down a wind turbine.